Periodic sharp wave complexes on EEG in Creutzfeldt-Jakob disease

What it looks like

Generalized bi- or triphasic sharp complexes repeating about once a second on a background that becomes progressively featureless. In ACNS terms these are GPDs; the label carries the clinical context. ²⁰

What it means at the bedside

With rapidly progressive dementia and myoclonus this supports sporadic CJD. Sensitivity is roughly two thirds over the course of the illness (64% in an autopsy-controlled series, specificity 91%), so a normal early EEG excludes nothing. Lateralized at first in some patients. ²⁰